With diversified functions and augmented performance of mobile phones, the ratio of the cost of handset's memory is increasingly rising, reaching the highest in some high-end phones and smart phones. Thus, it is necessary to study handset memory elaborately.

Growth Trend of Handset Memory Capacity

The average capacity of handset memory reached 180MB in 4Q, 2004. Then, the fast growth is maintained and the figure will be doubled to 415MB by Q2, 2006.

Roadmap for the Development of Handset Embedded Memory

In a handset, three areas require embedded memories. Firstly, RAM is needed for the temporary data storage of MCU and DSP. Secondly, NOR flash memory is used for storing system code of handset software. And the third one comes to NAND flash memory which is used for the storage of extended data. In general, RAM is a kind of volatile storage while NOR and NAND are both characterized by non-volatile storage.

Presently, RAM memories mostly adopt the form of PSRAM whose capacity is around  32MB-64MB. PSRAM can be divided into three types. Initially, CellularRAM is strongly supported by those companies: Hynix, Winbond, NanoAmp Solutions, Renesas, Micron, Infineon and Cypress. In the second place, COSMORAM is actively supported by Toshiba, NEC and Fujitsu. Thirdly, Samsung uses UtRAM. Because of its structure and features, the capacity of PSRAM can hardly exceed 256MB in a PCB of 108 square millimeters. And RAM with more than 256MB has to be supported by SDRAM. Many smart phones have already adopted the RAM with 512MB. In the future, PSRAM will be gradually declining while SDRAM will gain widespread popularity.

Key manufacturers such as Cypress, NEC, Toshiba and Mitsubishi which were formerly involved in handset-used PSRAM and SRAM cannot provide or manufacture SDRAM. Consequently, their competitiveness is greatly weakened. In comparison, manufacturers such as Hynix, Elpida, Infineon and Micron, which previously took up with DRAM production, began to embark on SDRAM production. Similar to RAM, NOR memory lacks of high density in spite of excellent code execution performance. Compared with NAND, NOR's low density hampers its development. NOR with 128MB-256MB or the maximum 512MB can be provided for low-end phones and medium-end phones. Once NOR's capacity exceeds 512MB, taking smart phones with outstanding performance for instance, manufacturers prefer to adopt NAND because NOR has a much higher cost and a relatively big-sized body. However, NAND has many defects such as the system being unable to start up directly. Concerning stability, there are hidden troubles such as bit-flipping, bad blocks and limited life in NAND. In addition, NAND adopts a non-standard interface and needs software management, which increases the cost of the system. Although this problem can be addressed through some structural methods, some technologies are required for the settlement of the above hidden troubles. M-SYSTEM helps NAND a lot to replace NOR. With the addition of software and hardware design (DiskOnChip) of M-SYSTEM, NAND flash memory can be equally used as NOR. At present, M-SYSTEM is mainly applied in smart phones or mobile phones with U-disk function. The relatively high price of M-SYSTEM hampers its development.

It will take three or four years for NAND to replace NOR. Non-smart top-grade 2.5G handsets adopts NOR ranging from 256MB to 320MB. Again, NOR capacity of general 3G mobile phones is around 256MB. There will be one or two years for NOR flash memory to exceed 512MB. In reality, 2.5G handsets will be the mainstream in the next three or four years, especially because domestic handset manufacturers pay much attention cost savings. NOR's capacity is currently led by 64-128MB.

NOR flash memory suppliers such as Sharp, SST and Spansion lack of NAND technology while other counterparts including Intel, STMicroelectronics, Renesas, Toshiba and Samsung are well experienced in NAND technology. Sharp and SST have decided not to set foot in the field of NOR. Only Spansion persists in developing ORNAND. The utilization efficiency of MCP flash memory is low and handset users can increase the capacity of NAND flash memory from 128MB to at least 1GB. In contrast, the utilization efficiency of micro hard disks can reach 100%.

At present, prices of 4GB flash memory and 8GB micro hard disks are about US$80 and US$70 respectively. If 4GB MCP adopted, users can actually utilize about 1GB. So, the demand of 2GB-above storage is better met by micro hard disks. No wonder that Samsung consecutively introduced handsets with 3GB, 4GB and 8GB micro hard disks. There will be at least three years before the average cost of handset memory equals to that of micro hard disk.

Some manufacturers also adopt independent flash memory chip to guarantee the utilization efficiency. But the current cost is comparatively high. Micro hard disks will be advantageous in the 4GB-above market in the next three years.

2 Handset embedded memory market in China
2.1 Overview of handset embedded memory market in China
2.2 Usage analysis of Motorola handset memory
2.3 Usage analysis of Nokia handset memory
2.4 Usage analysis of Samsung handset memory
2.5 Usage analysis of Bird handset memory
2.6 Usage analysis of SonyEricsson handset memory
2.7 Usage analysis of Lenovo handset memory
2.8 Usage analysis of Amoi handset memory
2.9 Usage analysis of LG handset memory
2.10 Usage analysis of TCL handset memory
2.11 Usage analysis of CECT handset memory
2.12 Usage analysis of other brand handset memory

3 Study on famous manufacturers of handset embedded memory
3.1 Samsung
3.2 Intel
3.3 Spansion
3.4 STMicroelectronics
3.5 Micron
3.6 Toshiba
3.7 Sharp
3.8 Elpida
3.9 Infineon
3.10 Renesas
3.11 Hynix
3.12 NEC
3.13 Cypress Semiconductor
3.14 SST
3.15 Winbond
3.16 Powerchip Semiconductor
3.17 ProMOS Technologies
3.18 Macronix
3.19 M-System
3.20 Elite Semiconductor
3.21 Etron Technology